A quilt is a thick cover for a bed, made from pieces of fabric that are stitched together and filled with padding. Quilt is also a verb, so you can quilt a quilt.
The simplest quilts have two layers of fabric that are sewn on either side of a layer of batting, a thin type of stuffing. Patchwork quilts have small pieces of cotton sewn into patterns, and the fabric is sewn over the batting with stitches that make decorative designs. A quilt was originally the same thing as a mattress, and the word comes from the Latin culcita, "mattress or bolster."